Can you describe this machine(s)? I'm not aware of a single device that tests keytones and glucose.
Generally speaking, you would test your glucose before eating, inject insulin, then test a while after eating (usually around 2 hrs after). With that said, your doctor should have advised you of what to do. Each person is different and we know very little about your situation. Did they say why they don't want you using your old device?
Side note: I remember your initial posts and a good bit of time has passed since then. I'm a bit concerned as to why your healthcare team isn't providing you with this information. This is extremely important information to understand as a type 1. Not only that, but it's information I would expect to receive immediately after my diagnosis.